How to increase maximum number of allowed Xvnc sessions ?

No matter what we do, under openSuse 11.0 no more than two concurrent vnc-viewer sessions are allowed to connect through xinetd.
In this forum exists a thread VNC Hell - openSUSE Forums
where the same problem was described at the end, but not answered. The only difference was that there were 5 connections allowed.
Has anybody a hint?